- 2080 Bhadra · 8 marks
Maintenance, rehabilitation, reconstruction; rigid failures
Short answer
Maintenance preserves serviceability (patching, sealing). Rehabilitation restores structural strength (overlay, recycling). Reconstruction builds new pavement. Rigid failures: transverse cracking (shrinkage, late sawing), corner breaks (pumping, unsupported corner), faulting (step at joint, poor load transfer), pumping, spalling, blow-up (blocked expansion joints).
Describe the term maintenance, rehabilitation and reconstruction. Describe the typical types of rigid pavement failure with sketches where possible.
Maintenance, rehabilitation and reconstruction
| Term | Meaning | Examples | Aim |
|---|---|---|---|
| Maintenance | Regular works to keep the road in serviceable condition without improving the original design | Patching, crack sealing, drain cleaning, resealing, regravelling | Preserve the existing condition and slow deterioration |
| Rehabilitation | Works that restore the structural strength and extend the life of an existing pavement, usually after major distress | Structural overlay (by deflection/IRC:81), recycling, partial reconstruction of failed areas, widening | Raise the load capacity to carry the traffic of the next design period |
| Reconstruction | Complete or near-complete removal and rebuilding of the pavement layers (and sometimes the geometry) at the end of its life | Removing all pavement layers and rebuilding to a new design | Provide a new pavement with a full design life |
Typical failures of rigid pavement
Typical types of failure of a cement concrete pavement:
| Failure | Description | Cause |
|---|---|---|
| Transverse cracking | Cracks across the slab | Late sawing of joints, joint spacing too long, thin slab, restrained shrinkage |
| Longitudinal cracking | Cracks along the lane | Differential settlement, warping, thin slab, poor subgrade support |
| Corner break (corner crack) | A triangular piece cut off at the slab corner by a crack meeting both edges, usually within about 1.5 m of the corner | Load at an unsupported corner, loss of support (pumping), poor load transfer |
| Diagonal cracking | Crack at about 45 degrees | Heavy corner loads, settlement |
| Punch-out / shattered slab | Slab breaks into many pieces | Heavy repeated loads, weak sub-base |
| Faulting | Step between slabs at a joint | Pumping, poor load transfer (dowel failure) |
| Pumping | Ejection of water and fines at joints | Water under the slab, loose subgrade, heavy traffic |
| Spalling | Breaking of joint edges | Incompressible material in joints, weak concrete, dowel misalignment |
| Blow-up (buckling) | Slab lifts and shatters in hot weather | Blocked expansion joints, insufficient expansion gap |
| Scaling and crazing | Flaking and map cracks on the surface | Over-finishing, poor curing, freeze-thaw |
| Joint seal failure | Loss of sealant, weeds in joints | Aged sealant, poor installation |
Faulting at a joint Corner break
______ +-------------+
______| step | |
joint | |
| crack -> /
+-----------/-+
Remedies include full-depth repair, slab replacement, dowel retrofit, grinding of faults, crack and joint resealing, undersealing (grouting) to fill voids, and improving drainage.
✓ Answer checked by Claude Opus 5.5 (high effort)
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